Significance of concurrent use of weekly cisplatin in carbon-ion radiotherapy for locally advanced adenocarcinoma of the uterine cervix: A propensity score-matched analysis.

Background: Although carbon-ion radiotherapy (C-ion RT) with concurrent chemotherapy (chemo-C-ion RT) is a promising treatment for adenocarcinoma (AC) of the uterine cervix, its long-term efficacy remains unclear. We evaluated the long-term significance of concurrent weekly cisplatin and C-ion RT for locally advanced AC of the uterine cervix.

Methods: We performed a pooled analysis of patients with stage IIB-IVA AC of the uterine cervix who underwent C-ion RT alone or chemo-C-ion RT between September 2007 and December 2018 at our institution. Patients received 74.4 Gy (relative biological effectiveness) with or without cisplatin (40 mg/m per week for up to 5 weeks), underwent no prior pelvic RT or systemic therapy, and had a performance status of 0-2. Propensity score matching was based on the year of diagnosis, regional lymph node metastasis, and stage.

Results: The matched cohort contained 26 patients who underwent C-ion RT and 26 who underwent chemo-C-ion RT. The median age and follow-up period were 57 (range, 28-79) years and 34 (range, 2-126) months, respectively. The 5-year overall survival rate was significantly better in the chemo-C-ion RT group (72%) than in the C-ion RT group (46%; P = .041). The 5-year distant metastatic-free rate was also significantly better in the chemo-C-ion RT group (66%) than in the C-ion RT group (41%; P = .048). The incidence of grade ≥ 3 late toxicities was comparable between the two groups.

Conclusions: Chemo-C-ion RT for locally advanced AC of the uterine cervix is associated with a long-term survival benefit.